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1
/*
2
 * FLAC (Free Lossless Audio Codec) decoder
3
 * Copyright (c) 2003 Alex Beregszaszi
4
 *
5
 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
8
 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
11
 *
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 * FFmpeg is distributed in the hope that it will be useful,
13
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
21

    
22
/**
23
 * @file libavcodec/flacdec.c
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 * FLAC (Free Lossless Audio Codec) decoder
25
 * @author Alex Beregszaszi
26
 *
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 * For more information on the FLAC format, visit:
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 *  http://flac.sourceforge.net/
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 *
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 * This decoder can be used in 1 of 2 ways: Either raw FLAC data can be fed
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 * through, starting from the initial 'fLaC' signature; or by passing the
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 * 34-byte streaminfo structure through avctx->extradata[_size] followed
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 * by data starting with the 0xFFF8 marker.
34
 */
35

    
36
#include <limits.h>
37

    
38
#include "libavutil/crc.h"
39
#include "avcodec.h"
40
#include "internal.h"
41
#include "bitstream.h"
42
#include "golomb.h"
43
#include "flac.h"
44

    
45
#undef NDEBUG
46
#include <assert.h>
47

    
48
#define MAX_CHANNELS 8
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#define MAX_BLOCKSIZE 65535
50

    
51
enum decorrelation_type {
52
    INDEPENDENT,
53
    LEFT_SIDE,
54
    RIGHT_SIDE,
55
    MID_SIDE,
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};
57

    
58
typedef struct FLACContext {
59
    FLACSTREAMINFO
60

    
61
    AVCodecContext *avctx;                  ///< parent AVCodecContext
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    GetBitContext gb;                       ///< GetBitContext initialized to start at the current frame
63

    
64
    int blocksize;                          ///< number of samples in the current frame
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    int curr_bps;                           ///< bps for current subframe, adjusted for channel correlation and wasted bits
66
    int sample_shift;                       ///< shift required to make output samples 16-bit or 32-bit
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    int is32;                               ///< flag to indicate if output should be 32-bit instead of 16-bit
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    enum decorrelation_type decorrelation;  ///< channel decorrelation type in the current frame
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    int got_streaminfo;                     ///< indicates if the STREAMINFO has been read
70

    
71
    int32_t *decoded[MAX_CHANNELS];         ///< decoded samples
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    uint8_t *bitstream;
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    unsigned int bitstream_size;
74
    unsigned int bitstream_index;
75
    unsigned int allocated_bitstream_size;
76
} FLACContext;
77

    
78
static const int sample_rate_table[] =
79
{ 0,
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  88200, 176400, 192000,
81
  8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
82
  0, 0, 0, 0 };
83

    
84
static const int sample_size_table[] =
85
{ 0, 8, 12, 0, 16, 20, 24, 0 };
86

    
87
static const int blocksize_table[] = {
88
     0,    192, 576<<0, 576<<1, 576<<2, 576<<3,      0,      0,
89
256<<0, 256<<1, 256<<2, 256<<3, 256<<4, 256<<5, 256<<6, 256<<7
90
};
91

    
92
static int64_t get_utf8(GetBitContext *gb)
93
{
94
    int64_t val;
95
    GET_UTF8(val, get_bits(gb, 8), return -1;)
96
    return val;
97
}
98

    
99
static void allocate_buffers(FLACContext *s);
100

    
101
int ff_flac_is_extradata_valid(AVCodecContext *avctx,
102
                               enum FLACExtradataFormat *format,
103
                               uint8_t **streaminfo_start)
104
{
105
    if (!avctx->extradata || avctx->extradata_size < FLAC_STREAMINFO_SIZE) {
106
        av_log(avctx, AV_LOG_ERROR, "extradata NULL or too small.\n");
107
        return 0;
108
    }
109
    if (AV_RL32(avctx->extradata) != MKTAG('f','L','a','C')) {
110
        /* extradata contains STREAMINFO only */
111
        if (avctx->extradata_size != FLAC_STREAMINFO_SIZE) {
112
            av_log(avctx, AV_LOG_WARNING, "extradata contains %d bytes too many.\n",
113
                   FLAC_STREAMINFO_SIZE-avctx->extradata_size);
114
        }
115
        *format = FLAC_EXTRADATA_FORMAT_STREAMINFO;
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        *streaminfo_start = avctx->extradata;
117
    } else {
118
        if (avctx->extradata_size < 8+FLAC_STREAMINFO_SIZE) {
119
            av_log(avctx, AV_LOG_ERROR, "extradata too small.\n");
120
            return 0;
121
        }
122
        *format = FLAC_EXTRADATA_FORMAT_FULL_HEADER;
123
        *streaminfo_start = &avctx->extradata[8];
124
    }
125
    return 1;
126
}
127

    
128
static av_cold int flac_decode_init(AVCodecContext *avctx)
129
{
130
    enum FLACExtradataFormat format;
131
    uint8_t *streaminfo;
132
    FLACContext *s = avctx->priv_data;
133
    s->avctx = avctx;
134

    
135
    avctx->sample_fmt = SAMPLE_FMT_S16;
136

    
137
    /* for now, the raw FLAC header is allowed to be passed to the decoder as
138
       frame data instead of extradata. */
139
    if (!avctx->extradata)
140
        return 0;
141

    
142
    if (!ff_flac_is_extradata_valid(avctx, &format, &streaminfo))
143
        return -1;
144

    
145
    /* initialize based on the demuxer-supplied streamdata header */
146
    ff_flac_parse_streaminfo(avctx, (FLACStreaminfo *)s, streaminfo);
147
    allocate_buffers(s);
148
    s->got_streaminfo = 1;
149

    
150
    return 0;
151
}
152

    
153
static void dump_headers(AVCodecContext *avctx, FLACStreaminfo *s)
154
{
155
    av_log(avctx, AV_LOG_DEBUG, "  Max Blocksize: %d\n", s->max_blocksize);
156
    av_log(avctx, AV_LOG_DEBUG, "  Max Framesize: %d\n", s->max_framesize);
157
    av_log(avctx, AV_LOG_DEBUG, "  Samplerate: %d\n", s->samplerate);
158
    av_log(avctx, AV_LOG_DEBUG, "  Channels: %d\n", s->channels);
159
    av_log(avctx, AV_LOG_DEBUG, "  Bits: %d\n", s->bps);
160
}
161

    
162
static void allocate_buffers(FLACContext *s)
163
{
164
    int i;
165

    
166
    assert(s->max_blocksize);
167

    
168
    if (s->max_framesize == 0 && s->max_blocksize) {
169
        // FIXME header overhead
170
        s->max_framesize= (s->channels * s->bps * s->max_blocksize + 7)/ 8;
171
    }
172

    
173
    for (i = 0; i < s->channels; i++) {
174
        s->decoded[i] = av_realloc(s->decoded[i],
175
                                   sizeof(int32_t)*s->max_blocksize);
176
    }
177

    
178
    if (s->allocated_bitstream_size < s->max_framesize)
179
        s->bitstream= av_fast_realloc(s->bitstream,
180
                                      &s->allocated_bitstream_size,
181
                                      s->max_framesize);
182
}
183

    
184
void ff_flac_parse_streaminfo(AVCodecContext *avctx, struct FLACStreaminfo *s,
185
                              const uint8_t *buffer)
186
{
187
    GetBitContext gb;
188
    init_get_bits(&gb, buffer, FLAC_STREAMINFO_SIZE*8);
189

    
190
    skip_bits(&gb, 16); /* skip min blocksize */
191
    s->max_blocksize = get_bits(&gb, 16);
192
    if (s->max_blocksize < 16) {
193
        av_log(avctx, AV_LOG_WARNING, "invalid max blocksize: %d\n",
194
               s->max_blocksize);
195
        s->max_blocksize = 16;
196
    }
197

    
198
    skip_bits(&gb, 24); /* skip min frame size */
199
    s->max_framesize = get_bits_long(&gb, 24);
200

    
201
    s->samplerate = get_bits_long(&gb, 20);
202
    s->channels = get_bits(&gb, 3) + 1;
203
    s->bps = get_bits(&gb, 5) + 1;
204

    
205
    avctx->channels = s->channels;
206
    avctx->sample_rate = s->samplerate;
207
    avctx->bits_per_raw_sample = s->bps;
208
    if (s->bps > 16)
209
        avctx->sample_fmt = SAMPLE_FMT_S32;
210
    else
211
        avctx->sample_fmt = SAMPLE_FMT_S16;
212

    
213
    s->samples  = get_bits_long(&gb, 32) << 4;
214
    s->samples |= get_bits(&gb, 4);
215

    
216
    skip_bits_long(&gb, 64); /* md5 sum */
217
    skip_bits_long(&gb, 64); /* md5 sum */
218

    
219
    dump_headers(avctx, s);
220
}
221

    
222
/**
223
 * Parse a list of metadata blocks. This list of blocks must begin with
224
 * the fLaC marker.
225
 * @param s the flac decoding context containing the gb bit reader used to
226
 *          parse metadata
227
 * @return non-zero if metadata is invalid
228
 */
229
static int metadata_parse(FLACContext *s)
230
{
231
    int i, metadata_last, metadata_type, metadata_size;
232

    
233
    skip_bits_long(&s->gb, 32);
234

    
235
    do {
236
        metadata_last = get_bits1(&s->gb);
237
        metadata_type = get_bits(&s->gb, 7);
238
        metadata_size = get_bits_long(&s->gb, 24);
239

    
240
        if (get_bits_count(&s->gb) + 8*metadata_size > s->gb.size_in_bits) {
241
            /* need more data. reset the bitstream reader and return. */
242
            init_get_bits(&s->gb, s->gb.buffer, s->gb.size_in_bits);
243
            break;
244
        }
245

    
246
        if (metadata_size) {
247
            switch (metadata_type) {
248
            case FLAC_METADATA_TYPE_STREAMINFO:
249
                if (!s->got_streaminfo) {
250
                    ff_flac_parse_streaminfo(s->avctx, (FLACStreaminfo *)s,
251
                                             s->gb.buffer+get_bits_count(&s->gb)/8);
252
                    allocate_buffers(s);
253
                    s->got_streaminfo = 1;
254
                }
255
            default:
256
                for (i = 0; i < metadata_size; i++)
257
                    skip_bits(&s->gb, 8);
258
            }
259
        }
260
    } while (!metadata_last);
261

    
262
    return 0;
263
}
264

    
265
static int decode_residuals(FLACContext *s, int channel, int pred_order)
266
{
267
    int i, tmp, partition, method_type, rice_order;
268
    int sample = 0, samples;
269

    
270
    method_type = get_bits(&s->gb, 2);
271
    if (method_type > 1) {
272
        av_log(s->avctx, AV_LOG_ERROR, "illegal residual coding method %d\n",
273
               method_type);
274
        return -1;
275
    }
276

    
277
    rice_order = get_bits(&s->gb, 4);
278

    
279
    samples= s->blocksize >> rice_order;
280
    if (pred_order > samples) {
281
        av_log(s->avctx, AV_LOG_ERROR, "invalid predictor order: %i > %i\n",
282
               pred_order, samples);
283
        return -1;
284
    }
285

    
286
    sample=
287
    i= pred_order;
288
    for (partition = 0; partition < (1 << rice_order); partition++) {
289
        tmp = get_bits(&s->gb, method_type == 0 ? 4 : 5);
290
        if (tmp == (method_type == 0 ? 15 : 31)) {
291
            tmp = get_bits(&s->gb, 5);
292
            for (; i < samples; i++, sample++)
293
                s->decoded[channel][sample] = get_sbits_long(&s->gb, tmp);
294
        } else {
295
            for (; i < samples; i++, sample++) {
296
                s->decoded[channel][sample] = get_sr_golomb_flac(&s->gb, tmp, INT_MAX, 0);
297
            }
298
        }
299
        i= 0;
300
    }
301

    
302
    return 0;
303
}
304

    
305
static int decode_subframe_fixed(FLACContext *s, int channel, int pred_order)
306
{
307
    const int blocksize = s->blocksize;
308
    int32_t *decoded = s->decoded[channel];
309
    int av_uninit(a), av_uninit(b), av_uninit(c), av_uninit(d), i;
310

    
311
    /* warm up samples */
312
    for (i = 0; i < pred_order; i++) {
313
        decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
314
    }
315

    
316
    if (decode_residuals(s, channel, pred_order) < 0)
317
        return -1;
318

    
319
    if (pred_order > 0)
320
        a = decoded[pred_order-1];
321
    if (pred_order > 1)
322
        b = a - decoded[pred_order-2];
323
    if (pred_order > 2)
324
        c = b - decoded[pred_order-2] + decoded[pred_order-3];
325
    if (pred_order > 3)
326
        d = c - decoded[pred_order-2] + 2*decoded[pred_order-3] - decoded[pred_order-4];
327

    
328
    switch (pred_order) {
329
    case 0:
330
        break;
331
    case 1:
332
        for (i = pred_order; i < blocksize; i++)
333
            decoded[i] = a += decoded[i];
334
        break;
335
    case 2:
336
        for (i = pred_order; i < blocksize; i++)
337
            decoded[i] = a += b += decoded[i];
338
        break;
339
    case 3:
340
        for (i = pred_order; i < blocksize; i++)
341
            decoded[i] = a += b += c += decoded[i];
342
        break;
343
    case 4:
344
        for (i = pred_order; i < blocksize; i++)
345
            decoded[i] = a += b += c += d += decoded[i];
346
        break;
347
    default:
348
        av_log(s->avctx, AV_LOG_ERROR, "illegal pred order %d\n", pred_order);
349
        return -1;
350
    }
351

    
352
    return 0;
353
}
354

    
355
static int decode_subframe_lpc(FLACContext *s, int channel, int pred_order)
356
{
357
    int i, j;
358
    int coeff_prec, qlevel;
359
    int coeffs[pred_order];
360
    int32_t *decoded = s->decoded[channel];
361

    
362
    /* warm up samples */
363
    for (i = 0; i < pred_order; i++) {
364
        decoded[i] = get_sbits_long(&s->gb, s->curr_bps);
365
    }
366

    
367
    coeff_prec = get_bits(&s->gb, 4) + 1;
368
    if (coeff_prec == 16) {
369
        av_log(s->avctx, AV_LOG_ERROR, "invalid coeff precision\n");
370
        return -1;
371
    }
372
    qlevel = get_sbits(&s->gb, 5);
373
    if (qlevel < 0) {
374
        av_log(s->avctx, AV_LOG_ERROR, "qlevel %d not supported, maybe buggy stream\n",
375
               qlevel);
376
        return -1;
377
    }
378

    
379
    for (i = 0; i < pred_order; i++) {
380
        coeffs[i] = get_sbits(&s->gb, coeff_prec);
381
    }
382

    
383
    if (decode_residuals(s, channel, pred_order) < 0)
384
        return -1;
385

    
386
    if (s->bps > 16) {
387
        int64_t sum;
388
        for (i = pred_order; i < s->blocksize; i++) {
389
            sum = 0;
390
            for (j = 0; j < pred_order; j++)
391
                sum += (int64_t)coeffs[j] * decoded[i-j-1];
392
            decoded[i] += sum >> qlevel;
393
        }
394
    } else {
395
        for (i = pred_order; i < s->blocksize-1; i += 2) {
396
            int c;
397
            int d = decoded[i-pred_order];
398
            int s0 = 0, s1 = 0;
399
            for (j = pred_order-1; j > 0; j--) {
400
                c = coeffs[j];
401
                s0 += c*d;
402
                d = decoded[i-j];
403
                s1 += c*d;
404
            }
405
            c = coeffs[0];
406
            s0 += c*d;
407
            d = decoded[i] += s0 >> qlevel;
408
            s1 += c*d;
409
            decoded[i+1] += s1 >> qlevel;
410
        }
411
        if (i < s->blocksize) {
412
            int sum = 0;
413
            for (j = 0; j < pred_order; j++)
414
                sum += coeffs[j] * decoded[i-j-1];
415
            decoded[i] += sum >> qlevel;
416
        }
417
    }
418

    
419
    return 0;
420
}
421

    
422
static inline int decode_subframe(FLACContext *s, int channel)
423
{
424
    int type, wasted = 0;
425
    int i, tmp;
426

    
427
    s->curr_bps = s->bps;
428
    if (channel == 0) {
429
        if (s->decorrelation == RIGHT_SIDE)
430
            s->curr_bps++;
431
    } else {
432
        if (s->decorrelation == LEFT_SIDE || s->decorrelation == MID_SIDE)
433
            s->curr_bps++;
434
    }
435

    
436
    if (get_bits1(&s->gb)) {
437
        av_log(s->avctx, AV_LOG_ERROR, "invalid subframe padding\n");
438
        return -1;
439
    }
440
    type = get_bits(&s->gb, 6);
441

    
442
    if (get_bits1(&s->gb)) {
443
        wasted = 1;
444
        while (!get_bits1(&s->gb))
445
            wasted++;
446
        s->curr_bps -= wasted;
447
    }
448
    if (s->curr_bps > 32) {
449
        ff_log_missing_feature(s->avctx, "decorrelated bit depth > 32", 0);
450
        return -1;
451
    }
452

    
453
//FIXME use av_log2 for types
454
    if (type == 0) {
455
        tmp = get_sbits_long(&s->gb, s->curr_bps);
456
        for (i = 0; i < s->blocksize; i++)
457
            s->decoded[channel][i] = tmp;
458
    } else if (type == 1) {
459
        for (i = 0; i < s->blocksize; i++)
460
            s->decoded[channel][i] = get_sbits_long(&s->gb, s->curr_bps);
461
    } else if ((type >= 8) && (type <= 12)) {
462
        if (decode_subframe_fixed(s, channel, type & ~0x8) < 0)
463
            return -1;
464
    } else if (type >= 32) {
465
        if (decode_subframe_lpc(s, channel, (type & ~0x20)+1) < 0)
466
            return -1;
467
    } else {
468
        av_log(s->avctx, AV_LOG_ERROR, "invalid coding type\n");
469
        return -1;
470
    }
471

    
472
    if (wasted) {
473
        int i;
474
        for (i = 0; i < s->blocksize; i++)
475
            s->decoded[channel][i] <<= wasted;
476
    }
477

    
478
    return 0;
479
}
480

    
481
static int decode_frame(FLACContext *s, int alloc_data_size)
482
{
483
    int blocksize_code, sample_rate_code, sample_size_code, assignment, i, crc8;
484
    int decorrelation, bps, blocksize, samplerate;
485

    
486
    blocksize_code = get_bits(&s->gb, 4);
487

    
488
    sample_rate_code = get_bits(&s->gb, 4);
489

    
490
    assignment = get_bits(&s->gb, 4); /* channel assignment */
491
    if (assignment < 8 && s->channels == assignment+1)
492
        decorrelation = INDEPENDENT;
493
    else if (assignment >=8 && assignment < 11 && s->channels == 2)
494
        decorrelation = LEFT_SIDE + assignment - 8;
495
    else {
496
        av_log(s->avctx, AV_LOG_ERROR, "unsupported channel assignment %d (channels=%d)\n",
497
               assignment, s->channels);
498
        return -1;
499
    }
500

    
501
    sample_size_code = get_bits(&s->gb, 3);
502
    if (sample_size_code == 0)
503
        bps= s->bps;
504
    else if ((sample_size_code != 3) && (sample_size_code != 7))
505
        bps = sample_size_table[sample_size_code];
506
    else {
507
        av_log(s->avctx, AV_LOG_ERROR, "invalid sample size code (%d)\n",
508
               sample_size_code);
509
        return -1;
510
    }
511
    if (bps > 16) {
512
        s->avctx->sample_fmt = SAMPLE_FMT_S32;
513
        s->sample_shift = 32 - bps;
514
        s->is32 = 1;
515
    } else {
516
        s->avctx->sample_fmt = SAMPLE_FMT_S16;
517
        s->sample_shift = 16 - bps;
518
        s->is32 = 0;
519
    }
520
    s->bps = s->avctx->bits_per_raw_sample = bps;
521

    
522
    if (get_bits1(&s->gb)) {
523
        av_log(s->avctx, AV_LOG_ERROR, "broken stream, invalid padding\n");
524
        return -1;
525
    }
526

    
527
    if (get_utf8(&s->gb) < 0) {
528
        av_log(s->avctx, AV_LOG_ERROR, "utf8 fscked\n");
529
        return -1;
530
    }
531

    
532
    if (blocksize_code == 0) {
533
        av_log(s->avctx, AV_LOG_ERROR, "reserved blocksize code: 0\n");
534
        return -1;
535
    } else if (blocksize_code == 6)
536
        blocksize = get_bits(&s->gb, 8)+1;
537
    else if (blocksize_code == 7)
538
        blocksize = get_bits(&s->gb, 16)+1;
539
    else
540
        blocksize = blocksize_table[blocksize_code];
541

    
542
    if (blocksize > s->max_blocksize) {
543
        av_log(s->avctx, AV_LOG_ERROR, "blocksize %d > %d\n", blocksize,
544
               s->max_blocksize);
545
        return -1;
546
    }
547

    
548
    if (blocksize * s->channels * (s->is32 ? 4 : 2) > alloc_data_size)
549
        return -1;
550

    
551
    if (sample_rate_code == 0)
552
        samplerate= s->samplerate;
553
    else if (sample_rate_code < 12)
554
        samplerate = sample_rate_table[sample_rate_code];
555
    else if (sample_rate_code == 12)
556
        samplerate = get_bits(&s->gb, 8) * 1000;
557
    else if (sample_rate_code == 13)
558
        samplerate = get_bits(&s->gb, 16);
559
    else if (sample_rate_code == 14)
560
        samplerate = get_bits(&s->gb, 16) * 10;
561
    else {
562
        av_log(s->avctx, AV_LOG_ERROR, "illegal sample rate code %d\n",
563
               sample_rate_code);
564
        return -1;
565
    }
566

    
567
    skip_bits(&s->gb, 8);
568
    crc8 = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
569
                  s->gb.buffer, get_bits_count(&s->gb)/8);
570
    if (crc8) {
571
        av_log(s->avctx, AV_LOG_ERROR, "header crc mismatch crc=%2X\n", crc8);
572
        return -1;
573
    }
574

    
575
    s->blocksize    = blocksize;
576
    s->samplerate   = samplerate;
577
    s->bps          = bps;
578
    s->decorrelation= decorrelation;
579

    
580
//    dump_headers(s->avctx, (FLACStreaminfo *)s);
581

    
582
    /* subframes */
583
    for (i = 0; i < s->channels; i++) {
584
        if (decode_subframe(s, i) < 0)
585
            return -1;
586
    }
587

    
588
    align_get_bits(&s->gb);
589

    
590
    /* frame footer */
591
    skip_bits(&s->gb, 16); /* data crc */
592

    
593
    return 0;
594
}
595

    
596
static int flac_decode_frame(AVCodecContext *avctx,
597
                            void *data, int *data_size,
598
                            const uint8_t *buf, int buf_size)
599
{
600
    FLACContext *s = avctx->priv_data;
601
    int tmp = 0, i, j = 0, input_buf_size = 0, bytes_read = 0;
602
    int16_t *samples_16 = data;
603
    int32_t *samples_32 = data;
604
    int alloc_data_size= *data_size;
605

    
606
    *data_size=0;
607

    
608
    if (s->max_framesize == 0) {
609
        s->max_framesize= FFMAX(4, buf_size); // should hopefully be enough for the first header
610
        s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);
611
    }
612

    
613
    if (1 && s->max_framesize) { //FIXME truncated
614
        if (s->bitstream_size < 4 || AV_RL32(s->bitstream) != MKTAG('f','L','a','C'))
615
            buf_size= FFMIN(buf_size, s->max_framesize - FFMIN(s->bitstream_size, s->max_framesize));
616
        input_buf_size= buf_size;
617

    
618
        if (s->bitstream_size + buf_size < buf_size || s->bitstream_index + s->bitstream_size + buf_size < s->bitstream_index)
619
            return -1;
620

    
621
        if (s->allocated_bitstream_size < s->bitstream_size + buf_size)
622
            s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->bitstream_size + buf_size);
623

    
624
        if (s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size) {
625
            memmove(s->bitstream, &s->bitstream[s->bitstream_index],
626
                    s->bitstream_size);
627
            s->bitstream_index=0;
628
        }
629
        memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size],
630
               buf, buf_size);
631
        buf= &s->bitstream[s->bitstream_index];
632
        buf_size += s->bitstream_size;
633
        s->bitstream_size= buf_size;
634

    
635
        if (buf_size < s->max_framesize && input_buf_size) {
636
            return input_buf_size;
637
        }
638
    }
639

    
640
    init_get_bits(&s->gb, buf, buf_size*8);
641

    
642
    /* check that there is at least the smallest decodable amount of data.
643
       this amount corresponds to the smallest valid FLAC frame possible. */
644
    if (buf_size < 24)
645
        goto end;
646

    
647
    /* check for inline header */
648
    if (show_bits_long(&s->gb, 32) == MKBETAG('f','L','a','C')) {
649
        if (metadata_parse(s)) {
650
            av_log(s->avctx, AV_LOG_ERROR, "invalid header\n");
651
            return -1;
652
        }
653
        goto end;
654
    }
655

    
656
    tmp = show_bits(&s->gb, 16);
657
    if ((tmp & 0xFFFE) != 0xFFF8) {
658
        av_log(s->avctx, AV_LOG_ERROR, "FRAME HEADER not here\n");
659
        while (get_bits_count(&s->gb)/8+2 < buf_size && (show_bits(&s->gb, 16) & 0xFFFE) != 0xFFF8)
660
            skip_bits(&s->gb, 8);
661
        goto end; // we may not have enough bits left to decode a frame, so try next time
662
    }
663
    skip_bits(&s->gb, 16);
664
    if (decode_frame(s, alloc_data_size) < 0) {
665
        av_log(s->avctx, AV_LOG_ERROR, "decode_frame() failed\n");
666
        s->bitstream_size=0;
667
        s->bitstream_index=0;
668
        return -1;
669
    }
670

    
671
#define DECORRELATE(left, right)\
672
            assert(s->channels == 2);\
673
            for (i = 0; i < s->blocksize; i++) {\
674
                int a= s->decoded[0][i];\
675
                int b= s->decoded[1][i];\
676
                if (s->is32) {\
677
                    *samples_32++ = (left)  << s->sample_shift;\
678
                    *samples_32++ = (right) << s->sample_shift;\
679
                } else {\
680
                    *samples_16++ = (left)  << s->sample_shift;\
681
                    *samples_16++ = (right) << s->sample_shift;\
682
                }\
683
            }\
684
            break;
685

    
686
    switch (s->decorrelation) {
687
    case INDEPENDENT:
688
        for (j = 0; j < s->blocksize; j++) {
689
            for (i = 0; i < s->channels; i++) {
690
                if (s->is32)
691
                    *samples_32++ = s->decoded[i][j] << s->sample_shift;
692
                else
693
                    *samples_16++ = s->decoded[i][j] << s->sample_shift;
694
            }
695
        }
696
        break;
697
    case LEFT_SIDE:
698
        DECORRELATE(a,a-b)
699
    case RIGHT_SIDE:
700
        DECORRELATE(a+b,b)
701
    case MID_SIDE:
702
        DECORRELATE( (a-=b>>1) + b, a)
703
    }
704

    
705
    *data_size = s->blocksize * s->channels * (s->is32 ? 4 : 2);
706

    
707
end:
708
    bytes_read = (get_bits_count(&s->gb)+7)/8;
709
    if (bytes_read > buf_size) {
710
        av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", bytes_read - buf_size);
711
        s->bitstream_size=0;
712
        s->bitstream_index=0;
713
        return -1;
714
    }
715

    
716
    if (s->bitstream_size) {
717
        s->bitstream_index += bytes_read;
718
        s->bitstream_size  -= bytes_read;
719
        return input_buf_size;
720
    } else
721
        return bytes_read;
722
}
723

    
724
static av_cold int flac_decode_close(AVCodecContext *avctx)
725
{
726
    FLACContext *s = avctx->priv_data;
727
    int i;
728

    
729
    for (i = 0; i < s->channels; i++) {
730
        av_freep(&s->decoded[i]);
731
    }
732
    av_freep(&s->bitstream);
733

    
734
    return 0;
735
}
736

    
737
static void flac_flush(AVCodecContext *avctx)
738
{
739
    FLACContext *s = avctx->priv_data;
740

    
741
    s->bitstream_size=
742
    s->bitstream_index= 0;
743
}
744

    
745
AVCodec flac_decoder = {
746
    "flac",
747
    CODEC_TYPE_AUDIO,
748
    CODEC_ID_FLAC,
749
    sizeof(FLACContext),
750
    flac_decode_init,
751
    NULL,
752
    flac_decode_close,
753
    flac_decode_frame,
754
    CODEC_CAP_DELAY,
755
    .flush= flac_flush,
756
    .long_name= NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
757
};